Method of sizing mineral fibers with a suspension of a polyamide resin and product produced thereby



United States Patent OfiFice 2,723,208 Patented Nov. 8, 1955 METHOD OF SIZING MINERAL FIBERS WITH A SUSPENSION OF A POLYAMIDE RESIN AND PRODUCT PRODUCED THEREBY Albert R. Morrison, Newark, Ohio, assignor to Owens- Corning Fiberglas Corporation, a corporation of Delaware No Drawing. Application September 13, 1951, Serial No. 246,503

9 Claims. (Cl. 117-126) This invention relates to the treatment of glass fibers and it is an object of this invention to produce a new and improved sized glass fiber and to provide a method and composition for use in producing same.

, In a properly sized glass fiber, the filaments hold together in strand form when the strand is drawn off of a winding drum for rewinding into packages or'twisting into yarns or the like. More specifically, in a sized strand in which the fibers are well bonded, the filaments of glass fibers are bonded together sufiiciently to eliminate the need for twisting in the process for multiple winding.

With present compositions for sizing glass fibers, such as are formulated with various combinations of starch, gelatin, polyvinyl alcohol and lubricants, or of polyvinyl acetate, methacrylato chromic chloride and a cationic lubricant, or the like, the glass fiber strand that is produced has been found to be lacking in abrasion resistance with the result that fuzziness is produced during twisting, plying, weaving or winding, and the yarn which is produced has a relatively low bonding strength which be comes more apparent byway of strand separation, especially when unwound from the drum onto which it is wound in forming.

It has been found that a desired degree of bonding to resist separation of fibers from the strand in forming and elimination of fuzzing during twisting and winding, but without unduly increasing the stiifness of the strand or yarn, can be fabricated by sizing the glass fibers, before or after forming, with an aqueous composition containing as its essential ingredients a cationic polyamide resin and a cationic butadiene-acrylonitrile copolymer. In addition to these essential ingredients the size composition may and preferably does contain a lubricant in the event that a certain amount of lubricity is desired between filaments in the improved strand or yarn further to enhance abrasion resistance and suppleness.

. The amount of solids which is desired to incorporate in the aqueous size composition usually is in excess of one percent by weight but it is desired to maintain the concentration at less than 7 percent by weight although more may be contained therein depending upon the amount of bonding desired balanced with the elfect of the increased amount of solids on stiffness and resilience of the strand or yarn formed therefrom. The ratio of polyamide resin to butadiene-acrylonitrile copolymer may range from 70 parts by weight polyamide to 30 parts by weight butadiene-acrylonitrile to 30 parts by weight polyamide to 70 parts by weight butadiene-acrylonitrile. The amount of butadiene-acrylonitrile may be less than the 30-70 ratio previously pointed out, however lesser amounts of the polyamide is undesirable because the slipperiness of the yarn increases so that winding into large packages and weaving into textile fabrics may be more difiicult. When present, the amount of lubricant may range from 0.1-2.0 percent by weight in the size composition. i p 7 It is preferred to make use of a cationic polyamide resin prepared by the condensation of dimerized vegetable oil acids with ethylene diamine or other diamines. More specifically, the polyamide resin having particular benefit in the practice of this invention is formed by the reaction of dimerized and trimerized linoleic and linolenic acids, such as are derived from soya bean oil, with ethylene liamine. The reaction product is formed into a cationic suspension in aqueous medium in the usual manner and it may be protected, while in suspension, with other plasticizer or modifying resins to enhance the water resistance, heat stability, flexibility and adhesion of the polyamide. Representative of resinous materials and plasticizers which may be added in small amounts to polyamide for the above purposes are dibutyl phthalate, tricresyl phosphate, rosin esters, waxes and parafiins, nitrocellulose and castor oil. The polyamide is present in the cationic suspensoid in amounts ranging from 35-40 percent by weight but the suspensoid may be diluted to the desired resin concentration for the size composition with water or with organic solvents of the type capable of dissolving the polyamide, such as methanol, ethanol, isopropanol, or solvents in which the polyamide has only limited solvency, if any, such as benzene, toluene, Xylene, Cellosolve, ethyl acetate, acetone, and the like.

The butadiene-acrylonitrile copolymer formed as a cationic component in a latex may be formed of butadiene and acrylonitrile present in the ratio of 25-35 parts by weight acrylonitrile to 75-65 parts by weight butadiene, such as is represented by the medium grade Hycar OR-25 manufactured by the B. F. Goodrich Chemical Company, and having a solids content of about 40-50 percent by Weight. Suitable cationic lubricants include the quaternary ammonium compounds formed with fatty acid groups of relatively long carbon length, such as cetyl, dimethyl benzyl ammonium chloride, dicoco dimethyl ammonium chloride or other onium lubricating cationic compounds of the type described in the Sloan Patents Nos. 2,338,206 and 2,356,542.

Application of the size composition may be made onto glass fibers cleaned, as by burning off or washing to remove previously applied size compositions or coatings, but it is preferred to apply the size composition onto the glass fiber filaments as an incidence to their forming operation. The technique and apparatus for sizing glass fibers in forming is fully described in the patent of Biefeld, No. 2,392,805, which issued on January 15, 1946.' Suffice it to say that a plurality of streams of molten glass issuing from openings in ,a bushing located on the underside of a glass melting furnace are attenuated into very fine filaments by a rapidly rotating drum upon which the filaments are wound in strand form. Intermediate the bushing and the Winding drum, the filaments are gathered together and pass over a roll applicator to which a constant stream of the size composition is fed and applied thereby to each of the filaments as they are gathered together to form strands.

The cationic polyamide suspensoid appears to dry as a powdery substance but can subsequently be fused at a temperature of about 250 F. to produce a protective film coating the fibers and loss of the powdery deposit of polyamide is avoided by reason of the fact that the butadiene-acrylonitrile component dries as a film which anchors the powders in position of use uniformly distributed over the glass fiber surfaces. Thus the sized glass fiber filaments may be allowed to air dry and function as a size for the glass fibers wherein the powdery polyamide apparently functions as a bearing surface to introduce lubricity while the butadiene-acrylonitrile copolymer binds the fibers sufliciently to provide a moderate degree of integration. It is desired, however, to heat the .sized glass fibers to a temperature of about 250 F. for fusion of the polyamide. in situ on the glass fiber surfaces. Fusion may be effected prior to or after the fibers have been wound upon the winding drum. Depending upon the temperature employed, exposure of the sized glass fibers for driving off diluent and fusion of the resinous material may range from a temperature of 225350 F. for a time ranging from minutes at the higher temperature to 2-3 hours at the lower temperature.

Although the exact mechanism for the preferential anchorage of the size components to the glass fiber surfaces has not been established, it is believed that the cationic components of the size become substantially immediately oriented with the negatively charged groups that predominate on the glass fiber surfaces so that protection is almost immediately efiected to the end that high elficiency is obtained in forming. The glass fiber bundles in strand or yarn form after fusion, prior to or after winding on the forming tube, can be unwound from the outside of the package in the ordinary twisting operation for yarn formation or can be drawn from the inside of the package for winding on a cone or a spool without twisting with little or no evidence of split fibers such as are characteristic of yarns formed of fibers sized with compositions of the type heretofore employed. The strand holds together when drawn off of the winding drum thereby to eliminate any of the troublesome characteristics secured with strands of the type heretofore produced with such other size compositions and the strands produced in accordance with this invention remain so well bonded that it has been found unnecessary to twist the strands in multiple winding. When twisted or wound, fuzzy ends which readily develop with strands treated with size compositions heretofore employed were not evident in such winding and twisting operations of fibers embodying features of this invention. More important, the yarns and strands and the fibrous structures produced therefrom were as much as 10-50 percent stronger than corresponding fibrous structures heretofore produced.

The following will illustrate the practice of this invention:

Example 1 Size composition:

5 percent by weight cationic polyamide suspensoid percent solids) 5 percent cationic butadiene-acrylonitrile copolymer in latex form containing about percent solids (Hycar OR-25) The polyamide component in the above size composition is prepared by the reaction of dimerized and trimerized linoleic and linolenic acid with ethylene diamine, as is marketed by General Mills under the designation A-100. The size composition was applied onto the glass fiber filaments in forming by a roll applicator and the strands were heated while on the forming tube in an oven having a temperature of 250 F. for two hours to drive off the diluent and fuse the size on the glass fiber surfaces. About 3.4 percent by weight solids were deposited on the glass fiber surfaces.

The twisting qualities of the strand produced in accordance with Example 1 were found to be good while the strand was still wet with the size composition. The twisting qualities wet were even better than the twisting qualities of the strand after it had been dried in an oven for 48 hours at a temperature of 130 F. or after the strand had been heated in the manner described for fusion.

Example 2 Size composition:

1.5 percent by weight polyamide cationic suspensoid,

35 percent solids (General Mills A-200) 3.5 percent by weight butadiene-acrylonitrile copolymer (25 parts acrylonitrile75 parts butadiene) percent solids) 0.2 percent by weight lubricant (cetyl dimethyl benzyl ammonium chloride) Application onto the glass fibers was made by a roll applicator in forming. About 2.5 percent by weight solids based upon the weight of glass fibers was deposited.

The wet strands had excellent twisting qualities and the twisting characteristics after drying at F. for 48 hours or fusing by exposure to 250 F. for two hours remained very good. The winding qualities of the wet strand were not as good as the dried strand and the final fused strand had excellent winding characteristics.

Example 3 Size composition:

3.5 percent by weight polyamide cationic suspensoid (40 percent solids) 1.5 percent by weight butadiene-acrylonitrile copolymer (40 percent solids) 0.2 percent by weight dicoco dimethyl ammonium chloride lubricant The size composition was applied to the glass fiber strands after they had been heated to a temperature of about 650 F. to remove coating compositions previously applied. The sized strands were then heated to a temperature of 300 F. for 20 minutes in order to fuse the polyamide on the glass fiber surfaces.

Although description herein has been made to the application of the size and composition in the treatment of glass fibers to improve the characteristics and strength properties of strands, yarns and fabrics formed thereof, there is reason to believe that corresponding results can be secured in the treatment of other fibers characterized by the presence of negative groups which predominate on the surfaces whereby proper coordination of the cationic compounds of the size composition with the fibers may be achieved. Such other fibers may include rock wool, asbestos and other mineral fibers.

It will be apparent that one of the characteristics of a size composition embodying features of this invention for the successful treatment of glass fibers resides in the presence of each of the components as cationic elements which render them more compatible with each other in the aqueous size composition and enables them substantially equally to be attracted to the glass fiber'surfaces to the end that uniform coverage and distribution of solids is secured thereon.

It will be understood that changes may be made in the specific ratios of materials in the size composition within the limitations set forth and that changes may be made in the manner of application and treatment with out departing from the spirit of the invention, especially as defined in the following claims.

I claim:

1. In the method of sizing mineral fiber filaments gathered into strands, the steps of coating the filaments with an aqueous composition containing a mixture of a cationic suspension of a polyamide resin and a cationic suspension of a butadiene-acrylonitrile copolymer, and drying the coating on the surfaces of the mineral fiber filaments to provide a layer of. the butadiene-acrylonitrile copolymer containing the polyamide distributed therein.

2. In the method of sizing glass fiber filaments gathered into strands, the steps of coating the filaments with an aqueous composition containing a mixture of a cationic suspension of a polyamide resin and a cationic suspension of a butadiene-acrylonitrile copolymer, drying the coating on the surfaces of the glass fiber filaments to provide a layer of the butadiene-acrylonitrile copolymer containing the polyamide distributed therein, and subsequently heating the coated glass fiber filaments to a temperature sulficient for fusion of the polyamide resin to form a substantially continuous protective film on the surfaces of the glass fiber filaments.

3. In the method of sizing glass fiber filaments gathered into strands, the steps of coating the filaments with an aqueous composition having from 1-7 percent solids consisting essentially of a cationic suspension of a polyamide resin in admixture with a cationic suspension of a. butadiene-acrylonitrile copolymer, and drying the coating on the surfaces of the glass fiber filaments to provide a layer formed of the butadiene-acrylonitrile copolymer having the polyamide resin distributed therein.

4. In the method of sizing glass fiber filaments, the steps of coating the filaments with an aqueous composition having from 1-7 percent by Weight solids consisting essentially of a cationic suspension of a polyamide resin in admixture with a cationic suspension of a butadieneacrylonitrile copolymer present in the ratio of 30-70 parts by weight polyamide resin to 70-30 parts by weight of the cationic butadiene-acrylonitrile copolymer, and drying the coating on the surfaces of the glass fiber filaments to deposit the butadiene-acrylonitrile copolymer as a layer having the polyamide resin distributed therein.

5 In the method of sizing glass fiber filaments, the steps of coating the filaments with an aqueous composition containing a cationic suspension of a polyamide resin in admixture with a cationic butadiene-acrylonit1ile copolymer and a cationic lubricant, and drying the coating on the surfaces of the glass fiber filaments to deposit the butadiene-acrylonitrile copolymer and lubricant as a layer having the polyamide resin distributed therein.-

6. The method of sizing glass fibers as claimed in claim 1 in which the polyamide resin comprises the condensation reaction product of dimerized and trimerized vegetable oil acids with ethylene diamine.

7. The method of sizing glass fibers as claimed in claim 5 in which the cationic lubricant comprises a quaternary ammonium compound containing one or more large chain fatty acid groups.

8. Sized mineral fibers in which the sizing on the fiber surfaces consists of a coating in the form of the residue of a mixture of a cationic suspension of a polyamide resin and a cationic suspension of a butadiene-acrylonitrile copolymer.

9. Sized glass fibers in which the sizing on the glass fiber surfaces consists of a coating comprising a mixture of a cationic suspension of a butadiene-acrylonitrile copolymer and a cationic suspension of a polyamide resin in which the coating has been heated to fusion of the polyamide resin.

References Cited in the file of this patent UNITED STATES PATENTS 2,518,148 Jordan Aug. 8, 1940 2,424,588 Sparks et al. July 29, 1947 2,446,119 White et a1. July 27, 1948 2,550,465 Gorski Apr. 24, 1951 2,563,289 Steinman Aug. 7, 1951 2,633,432 Kenneway Mar. 31, 1953 FOREIGN PATENTS 555,481 Great Britain Aug. 25, 1943 OTHER REFERENCES Polyamide Resin Suspensoids, General Mills, Inc., October 20, 1954 (only p. 6 relied on). 

1. IN THE METHOD OF SIZING MINERAL FIBER FILAMENTS GATHERED INTO STRANDS, THE STEPS OF COATING THE FILAMENTS WITH AN AQUEOUS COMPOSITION CONTAINING A MIXTURE OF A CATIONIC SUSPENSION OF A POLYAMIDE RESIN AND A CATIONIC SUSPENSION OF A BUTADIENE-ACRYLONITRILE COPOLYMER, AND DRYING THE COATING ON THE SURFACES OF THE MINERAL FIBER FILAMENTS TO PROVIDE A LAYER OF THE BUTADIENE-ACRYLONITRILE COPOLYMER CONTAINING THE POLYAMIDE DISTRIBUTED THEREIN. 